Jq
From wikinotes
parse json on the commandline.
TODO:
the official docs are very good, but syntax could be documented consistently with other languages. (ex: datatypes etc)
Documentation
official docs https://stedolan.github.io/jq/manual/ basic filters docs https://stedolan.github.io/jq/manual/#Basicfilters homepage https://stedolan.github.io/jq/
Usage
Parameters
jq ${params..} ${query} [${file}] jq \ -r `# 'raw' remove quotes from retrieved strings` \ -e `# if result is 'true' exitcode is 0, if 'false' exitcode is 1`Basics
# print w/ syntaxhighlighting echo '{"one": 1, "two": {"a": "A"}}' \ | jq # get key ["one"] echo '{"one": 1, "two": {"a": "A"}}' \ | jq '.one' # 1 # get nested-key ["two"]["a"] echo '{"one": 1, "two": {"a": "A"}}' \ | jq '.two.a' # "A" # get list item at index 1 echo '["a", "b", "c"]' \ | jq '.[1]' # "b" # get 'a' key form every dict in list echo '{"list": [{"a": 1}, {"a": 2}]}' \ | jq '.list[].a'Working with Types
# merge sub-objects with parent object echo '{ "categories": { "foo": { {"a": 1, "b": 2} }, "bar": { {"a": 3, "b": 4} } } }' \ | jq '.categories | with_entries | map({ category: .key, a: .a })' # [ # { "category": "foo", "a" 1 }, # { "category": "bar", "a" 3 } # ]Filters
jq '.' # obj jq '.one' # obj["one"] jq '.one?' # obj["one"] (but no error if not exist) jq '.one.two' # obj["one"]["two"] jq '.[1]' # obj[1] jq '.[5:10]' # list-items 5-10 jq '.[] | select(.name == "foo") # all dicts in list where name=="foo" jq '.[] | select(.id == (242, 1, 123)) # all dicts where id in (242, 1, 123) jq 'any(.[]; .id == "foo")' # true if any dict in list contains {"id": "foo"} jq '.[].name | select(startswith("foo"))' # all name keys from dicts that start with "foo" jq '.[] | with_entries(select(.key | in({"id": 1, "name": 1})))' # return subset of keys from dict (only: id, name)Expressions
Selections within
()
are evaluated as expressionsConditionals
Combined with
jq -e
, you can return true/false and map to an exitcode.echo '{"a": "foo"}' \ | jq -e '.a == "foo"' \ && echo "success"Operators
Used in expressions
+ - * / %Transform
You can compose new objects from the input object.
jq '{"fullname": (.firstname + .lastname)}'Comments
Neither json nor
jq
support comments.
It's hacky, but you could pre-process the object to strip them, however.echo '{ // syntax-highlight as javascript "local_path": "/home/you", // your home dir // a network path "netwk_path": "//10.1.0.5/music" }' \ | sed 's?//[^"]*$??' | jq '.one'